1. Technical Field
The present invention relates to apparatus for performing determination of immune reactants in biological fluids and, more particularly, for performing in vitro semi-quantitative determinations of allergen-specific (e.g., IgE, IgG, etc.) antibodies in human serum.
2. Discussion of the Prior Art
It is known that, in humans, immediate type allergic reactions (e.g., hay fever, extrinsic asthma, or atopic eczema) are mediated by reaginic antibodies belonging to the IgE class of immunoglobulins. Atopic individuals exposed to allergens such as pollens, dust or animal danders, produce specific IgE antibodies against these allergens. The present invention is concerned with determining the presence of circulating allergen-specific IgE antibodies in the blood plasma or serum of an affected individual.
A technique for accomplishing this result is known in the prior art as described in U.S. Pat. No. 3,720,760 (Bennich et al), the disclosure of which is expressly incorporated herein, in its entirety, by this reference. Specifically, Bennich et al disclose an in vitro method for analyzing a test sample (e.g., a body fluid such as blood serum or blood plasma) by contacting, in vitro, the test sample with a water insoluble polymer to which a test allergen has been bound. A reaction takes place between the test allergen on the polymer and the reagin-IgE directed against the allergen so that the reagin is bound to the test allergen on the insoluble polymer. The polymer, in sheet form, and with the test allergen and the reagin-IgE attached thereto,may then be contacted with antibodies against reagin-IgE that have been labeled with a radiation-emitting atom or group. The insoluble polymer sheet is separated from the fluid, whereupon the radiation emitted from the insoluble polymer with the substances attached thereto, or the radiation emitted from the separated fluid, is measured. If the reagin-IgE directed against the allergen is present in the sample, labeled reagin is bound to the insoluble phase which then emits radiation. The latter increases with increasing concentration of the reagin-IgE in the test sample. The radiation of the liquid phase decreases with increasing concentration of the reagin-IgE as more labeled reagin is bound to the insoluble phase. The measured radiation values obtained in this procedure for the test sample can be compared with values for control samples. If instead of radioimmunoassay (RIA) techniques, one were to use enzyme-immunoassay (EIA), color intensity, rather than radiation, becomes the measured parameter.
The use of polymer sheets as a vehicle to which the test allergen is bound, and to which the allergen-specific antibodies attach, becomes unwieldy in practice. The present invention is concerned with providing apparatus that greatly simplifies the portion of the Bennich et al method during which the polymer, to which a test allergen has been bound, is inserted into the test serum to permit circulating allergen-specific IgE antibodies to attach to the bound allergen.